Ultrasound diagnosis apparatus and controlling method

ABSTRACT

An ultrasound diagnosis apparatus includes: a scan controlling unit that exercises control to perform a first scanning process by transmitting an ultrasound wave in a first direction and a second scanning process by transmitting an ultrasound wave in each of a plurality of directions; an image generating unit that generates a first ultrasound image and second ultrasound images from the first and the second scanning processes, respectively; an image generation controlling unit that has a needle image generated, based on an analysis result on the brightness distribution of each member of a group of images based on the first ultrasound image and the second ultrasound images or an analysis result on the brightness distribution of each of the second ultrasound images; an image synthesizing unit that generates a synthesized image from the first ultrasound image and the needle image; and a display controlling unit that displays the synthesized image.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. patent applicationSer. No. 13/435,346, filed on Mar. 30, 2012, which is based upon andclaims the benefit of priority from Japanese Patent Application No.2011-081986, filed on Apr. 1, 2011, and Japanese Patent Application No.2012-041505, filed on Feb. 28, 2012, the entire contents of all of whichare incorporated herein by reference.

FIELD

Embodiments described herein relate generally to an ultrasound diagnosisapparatus and a controlling method.

BACKGROUND

Conventionally, ultrasound diagnosis apparatuses have often been usedfor performing a test on a tissue in a subject's body and providingRadio Frequency Ablation (RFA) treatments where a puncture process isperformed while using a puncture needle, because ultrasound diagnosisapparatuses are capable of displaying an ultrasound image capturedimmediately underneath an ultrasound probe in a real-time manner.Depending on where the lesion is positioned and the angle at which apuncture needle is inserted, it can be difficult to see the punctureneedle in some situations. In those situations, the puncture process isperformed while checking on how the tissue moves when, for example, thepuncture needle is moved around.

To cope with those situations, a technique is known these days by which,to improve the visibility of a puncture needle during a punctureprocess, an ultrasound beam is radiated perpendicularly to the punctureneedle by performing an oblique scanning process, so as to generate anultrasound image (a needle image) in which the puncture needle isrendered with a high level of brightness. Further, another technique isalso known by which, without performing the oblique scanning process, aregular ultrasound scanning process is performed so as to generate, inaddition to a needle image, an ultrasound image (a subject-body image)in which a tissue in the subject's body is rendered and so as togenerate and display a synthesized image obtained by synthesizingtogether the needle image and the subject-body image. According to thistechnique, when the synthesized image is generated, one or more of thefollowing processes are performed: a process to add together the needleimage and the subject-body image; a process to superimpose the imageswith one another by averaging the pixel values for each of the pixels;and a process to hold the maximum value of brightness levels for each ofthe pixels (a maximum brightness value holding process or a Max-Holdprocess).

It should be noted, however, that the tissue in the subject's bodyrendered in the ultrasound image generated by performing the obliquescanning process has lower image quality than in an image obtained byperforming a non-oblique scanning process, due to a side-lobe effect orthe like. For this reason, although the visibility of the punctureneedle in the synthesized image is improved to some extent, thediagnosability using the synthesized image is lower because it is notpossible to perform a substantive observation on a lesion in the tissuein an optimal manner. In other words, a phenomenon occurs where,although the puncture needle is easier to see because the ultrasoundbeam is perpendicularly applied to the puncture needle, informationabout the tissue in the subject's body becomes degraded due tooccurrence of, for example, a grating side-lobe caused by problemsrelated to the shape of the beam or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram for explaining a configuration of an ultrasounddiagnosis apparatus according to a first embodiment;

FIG. 2 is a drawing for explaining a scan controlling unit according tothe first embodiment;

FIG. 3 is a drawing for explaining an image generating unit according tothe first embodiment;

FIG. 4 is a drawing for explaining an extracting unit according to thefirst embodiment;

FIG. 5 is a drawing for explaining an image synthesizing unit accordingto the first embodiment;

FIG. 6 is a flowchart for explaining a process performed by theultrasound diagnosis apparatus according to the first embodiment;

FIG. 7 is a diagram for explaining a configuration of a controlling unitaccording to a second embodiment;

FIG. 8 is a drawing for explaining an adjusting unit according to thesecond embodiment;

FIGS. 9 and 10 are drawings for explaining a selecting unit according toa third embodiment;

FIG. 11 is a flowchart for explaining a process performed by anultrasound diagnosis apparatus according to the third embodiment;

FIGS. 12A and 12B are drawings for explaining a process performed by acontrolling unit according to a fourth embodiment;

FIG. 13 is a drawing for explaining a modification example of the imagesynthesizing unit; and

FIGS. 14A and 14B are drawings for explaining a modification example ofthe scan controlling unit.

DETAILED DESCRIPTION

According to one embodiment, an ultrasound diagnosis apparatus includesa scan controlling unit, an image generating unit, an image generationcontrolling unit, an image synthesizing unit and a display controllingunit. The scan controlling unit is configured to, when performing anultrasound scanning process on a subject into whom a puncture needle hasbeen inserted, cause an ultrasound probe to perform a first scanningprocess by transmitting an ultrasound wave in a first direction withrespect to a surface of a vibrator for a purpose of taking an image of atissue of the subject and a second scanning process by transmitting anultrasound wave in each of a plurality of directions with respect to thesurface of the vibrator. The image generating unit is configured togenerate a first ultrasound image by using a reflected wave received bythe ultrasound probe during the first scanning process and to generate agroup of second ultrasound images that are ultrasound imagescorresponding to the plurality of directions by using reflected wavesreceived by the ultrasound probe during the second scanning process. Theimage generation controlling unit is configured to control the imagegenerating unit so as to generate a needle image in which the punctureneedle is rendered with a high level of brightness, based on an analysisresult obtained by analyzing a brightness distribution of each member ofa group of images based on the first ultrasound image and the group ofsecond ultrasound images or based on an analysis result obtained byanalyzing a brightness distribution of each member of the group ofsecond ultrasound images. The image synthesizing unit configured togenerate a synthesized image by synthesizing together the firstultrasound image and the needle image generated by the image generatingunit. The display controlling unit configured to exercise control sothat the synthesized image generated by the image synthesizing unit isdisplayed on a predetermined display unit.

In the following sections, exemplary embodiments of an ultrasounddiagnosis apparatus will be explained in detail, with reference to theaccompanying drawings.

First, a configuration of an ultrasound diagnosis apparatus according toa first embodiment will be explained. FIG. 1 is a diagram for explainingthe configuration of the ultrasound diagnosis apparatus according to thefirst embodiment. As shown in FIG. 1, the ultrasound diagnosis apparatusaccording to the first embodiment includes an ultrasound probe 1, amonitor 2, an input device 3, and an apparatus main body 10.

The ultrasound probe 1 is detachably connected to the apparatus mainbody 10. The ultrasound probe 1 includes a plurality of piezoelectricvibrators, which generate an ultrasound wave based on a drive signalsupplied from a transmitting and receiving unit 11 included in theapparatus main body 10 (explained later). Further, the ultrasound probe1 receives a reflected wave from an examined subject P and converts thereceived reflected wave into an electric signal. Further, the ultrasoundprobe 1 includes matching layers included in the piezoelectricvibrators, as well as a backing member that prevents ultrasound wavesfrom propagating rearward from the piezoelectric vibrators.

When an ultrasound wave is transmitted from the ultrasound probe 1 tothe subject P, the transmitted ultrasound wave is repeatedly reflectedon a surface of discontinuity of acoustic impedances at a tissue in thebody of the subject P and is received as a reflected-wave signal by theplurality of piezoelectric vibrators included in the ultrasound probe 1.The amplitude of the received reflected-wave signal is dependent on thedifference between the acoustic impedances on the surface ofdiscontinuity on which the ultrasound wave is reflected. When thetransmitted ultrasound pulse is reflected on the surface of a flowingbloodstream or a cardiac wall, the reflected-wave signal is, due to theDoppler effect, subject to a frequency shift, depending on a velocitycomponent of the moving members with respect to the ultrasound wavetransmission direction (hereinafter, “ultrasound transmissiondirection”).

The first embodiment is applicable to a situation where the ultrasoundprobe 1 shown in FIG. 1 is configured with a one-dimensional ultrasoundprobe in which the plurality of piezoelectric vibrators are arranged ina row, to a situation where the ultrasound probe 1 is configured with aone-dimensional ultrasound probe in which the plurality of piezoelectricvibrators arranged in a row are mechanically oscillated, and to asituation where the ultrasound probe 1 is configured with atwo-dimensional ultrasound probe in which the plurality of piezoelectricvibrators are arranged two-dimensionally in a matrix formation.

Further, a puncture adapter 1 a is attached to the ultrasound probe 1according to the first embodiment so that a medical doctor is able toperform a puncture process for, for example, performing a test on atissue in the subject's body or providing a radio frequency ablationtreatment, while referring to an ultrasound image. Further, a punctureneedle 1 b is attached to the puncture adapter 1 a. While referring tothe ultrasound image, the medical doctor inserts the puncture needle 1 battached to the puncture adapter 1 a to reach a target site of thesubject P.

The input device 3 includes a mouse, a keyboard, a button, a panelswitch, a touch command screen, a foot switch, a trackball, and thelike. The input device 3 receives various types of setting requests froman operator of the ultrasound diagnosis apparatus and transfers thereceived various types of setting requests to the apparatus main body10. For example, when the operator presses an end button or a freezebutton included in the input device 3, the transmission and reception ofthe ultrasound wave is ended so that the ultrasound diagnosis apparatusaccording to the first embodiment goes into a temporarily-halted state.In addition, the operator is able to set and change, via the inputdevice 3, oblique angles used in ultrasound transmissions for performinga second scanning process (an oblique scanning process), which isexplained later.

The monitor 2 displays a Graphical User Interface (GUI) used by theoperator of the ultrasound diagnosis apparatus to input the varioustypes of setting requests through the input device 3 and displays anultrasound image generated by the apparatus main body 10.

The apparatus main body 10 is an apparatus that generates the ultrasoundimage based on the reflected wave received by the ultrasound probe 1. Asshown in FIG. 1, the apparatus main body 10 includes the transmittingand receiving unit 11, a B-mode processing unit 12, a Doppler processingunit 13, an image generating unit 14, an image memory 15, an imagesynthesizing unit 16, an internal storage unit 17, and a controllingunit 18.

The transmitting and receiving unit 11 includes a trigger generatingcircuit, a delaying circuit, a pulser circuit, and the like and suppliesthe drive signal to the ultrasound probe 1. The pulser circuitrepeatedly generates a rate pulse for forming a transmission ultrasoundwave at a predetermined rate frequency. Further, the delaying circuitapplies a delay period that is required to converge the ultrasound wavegenerated by the ultrasound probe 1 into the form of a beam and todetermine transmission directionality and that corresponds to each ofthe piezoelectric vibrators, to each of the rate pulses generated by thepulser circuit. Further, the trigger generating circuit applies a drivesignal (a drive pulse) to the ultrasound probe 1 with timing based onthe rate pulses. In other words, the delaying circuit arbitrarilyadjusts the directions of the transmissions from the piezoelectricvibrator surfaces, by varying the delay periods applied to the ratepulses.

The transmitting and receiving unit 11 has a function to be able toinstantly change the transmission frequency, the transmission drivevoltage, and the like, for the purpose of executing a predeterminedscanning sequence based on an instruction from the controlling unit 18(explained later). In particular, the configuration to change thetransmission drive voltage is realized by using a linear-amplifier-typetransmitting circuit of which the value can be instantly switched or byusing a mechanism configured to electrically switch between a pluralityof power source units.

Further, the transmitting and receiving unit 11 includes an amplifiercircuit, an Analog/Digital (A/D) converter, an adder, and the like andgenerates reflected-wave data by performing various types of processeson the reflected-wave signal received by the ultrasound probe 1. Theamplifier circuit amplifies the reflected-wave signal for each ofchannels and performs a gain correcting process thereon. The A/Dconverter applies an A/D conversion to the gain-corrected reflected-wavesignal and further applies thereto a delay period required to determinereception directionality. The adder generates the reflected-wave data byperforming an adding process on reflected-wave signals, based on theapplied delay periods. As a result of the adding process performed bythe adder, reflected components from the direction corresponding to thereception directionality of the reflected-wave signal are emphasized.

In this manner, the transmitting and receiving unit 11 controls thetransmission directionality and the reception directionality in thetransmission and the reception of the ultrasound wave. The transmittingand receiving unit 11 has a function to be able to instantly changedelay information, the transmission frequency, the transmission drivevoltage, the number of aperture elements, and the like, under thecontrol of the controlling unit 18 (explained later). Further, thetransmitting and receiving unit 11 is also able to transmit and receivea waveform that is different for each of the frames or for each of therates.

The B-mode processing unit 12 receives the reflected-wave data from thetransmitting and receiving unit 11 and generates data (B-mode data) inwhich the strength of each signal is expressed by a degree ofbrightness, by performing a logarithmic amplification, an envelopedetection process, and the like on the received reflected-wave data.

The Doppler processing unit 13 receives the reflected-wave data from thetransmitting and receiving unit 11, extracts bloodstreams, tissues, andcontrast echo components under the influence of the Doppler effect byperforming a frequency analysis so as to obtain velocity informationfrom the received reflected-wave data, and further generates data(Doppler data) obtained by extracting moving member information such asan average velocity, the dispersion, the power, and the like for aplurality of points. The data generated by the B-mode processing unit 12and the Doppler processing unit 13 may be referred to as raw data.

The image generating unit 14 generates an ultrasound image from the datagenerated by the B-mode processing unit 12 and the Doppler processingunit 13. More specifically, from the B-mode data generated by the B-modeprocessing unit 12, the image generating unit 14 generates the B-modeimage in which the strength of the reflected wave is expressed by adegree of brightness. Further, from the Doppler data generated by theDoppler processing unit 13, the image generating unit 14 generates anaverage velocity image, a dispersion image, and a power image,expressing the moving member information, or a color Doppler image,which is an image combining these images.

Further, the image generating unit 14 is also able to generate asynthesized image by synthesizing text information of variousparameters, scale graduations, body marks, and the like with anultrasound image.

In this situation, the image generating unit 14 converts (by performinga scan convert process) a scanning line signal sequence from anultrasound scan into a scanning line signal sequence in a video formatused by, for example, television and generates the ultrasound imageserving as a displayed image. Further, as various types of imageprocessing processes other than the scan convert process, the imagegenerating unit 14 performs, for example, an image processing process (asmoothing process) to re-generate a brightness average-value image whileusing a plurality of image frames resulting from the scan convertprocess and an image processing process (an edge emphasizing process) byemploying a differential filter within an image.

Further, the image generating unit 14 has installed therein a storagememory for storing therein image data and is able to perform a processof reconstructing a three-dimensional image. Further, after a diagnosisis made, the operator is able to acquire, for example, an image recordedduring a medical examination, out of the storage memory installed in theimage generating unit 14.

The image synthesizing unit 16 synthesizes text information of variousparameters, scale graduations, body marks, and the like with theultrasound image generated by the image generating unit 14 and outputsthe result to the monitor 2 as a video signal. In the first embodiment,the image synthesizing unit 16 generates a synthesized image obtained bysynthesizing together a subject-body image and a needle image. Thesynthesized image generated by the image synthesizing unit 16 accordingto the first embodiment will be explained in detail later.

The image memory 15 is a memory for storing therein the ultrasound imagegenerated by the image generating unit 14 and the synthesized imagegenerated by the image synthesizing unit 16. For example, the imagememory 15 stores therein ultrasound images corresponding to a pluralityof frames immediately prior to pressing of the freeze button. Theultrasound diagnosis apparatus is also able to display ultrasound movingimages by successively displaying (called “cine display”) the imagesstored in the image memory 15.

The internal storage unit 17 stores therein various types of data suchas a control computer program (hereinafter, “control program”) torealize ultrasound transmissions and receptions, image processing, anddisplay processing, as well as diagnosis information (e.g., patients'IDs, medical doctors' observations), diagnosis protocols, and varioustypes of body marks. Further, the internal storage unit 17 may be used,as necessary, for storing therein any of the images stored in the imagememory 15. Furthermore, the data stored in the internal storage unit 17may be transferred to any external peripheral device via an interfacecircuit (not shown).

Further, the internal storage unit 17 according to the first embodimentstores therein the angle at which the puncture needle 1 b is attached tothe puncture adapter 1 a, as a puncture angle of the puncture needle 1b. For example, when the puncture adapter 1 a is attached, the internalstorage unit 17 stores therein an attachment angle “A” of the punctureadapter 1 a, as an insertion angle “A” of the puncture needle 1 b.

The controlling unit 18 controls the entire processes performed by theultrasound diagnosis apparatus. More specifically, based on the varioustypes of setting requests input by the operator via the input device 3and various types of control programs and various types of data readfrom the internal storage unit 17, the controlling unit 18 controlsprocesses performed by the transmitting and receiving unit 11, theB-mode processing unit 12, the Doppler processing unit 13, the imagegenerating unit 14, and the image synthesizing unit 16. For example, ascan controlling unit 18 a shown in FIG. 1 controls an ultrasoundscanning process performed by the ultrasound probe 1, via thetransmitting and receiving unit 11. Further, a display controlling unit18 d shown in FIG. 1 exercises control so that the ultrasound images andthe synthesized images stored in the image memory 15 are displayed onthe monitor 2.

In addition to the scan controlling unit 18 a and the displaycontrolling unit 18 d, the controlling unit 18 according to the firstembodiment also includes an image generation controlling unit 181, asshown in FIG. 1. As shown in FIG. 1, the image generation controllingunit 181 includes a selecting unit 18 b and an extracting unit 18 c. Theprocesses performed by the scan controlling unit 18 a, the selectingunit 18 b, the extracting unit 18 c, and the display controlling unit 18d in the first embodiment will be explained in detail later.

An overall configuration of the ultrasound diagnosis apparatus accordingto the first embodiment has thus been explained. The ultrasounddiagnosis apparatus according to the first embodiment configured asdescribed above generates an ultrasound image (a B-mode image) by takingan image of a tissue in the body of the subject P into whom the punctureneedle 1 b has been inserted. Further, the ultrasound diagnosisapparatus according to the first embodiment generates an ultrasoundimage in which visibility of both the tissue in the subject's body andthe puncture needle is improved, as a result of controlling processesperformed by the controlling unit 18, which are explained in detailbelow. For example, when the operator presses a puncture mode startbutton included in the input device 3, the ultrasound diagnosisapparatus according to the first embodiment starts the process describedbelow. As another example, when the operator presses a puncture mode endbutton included in the input device 3, the ultrasound diagnosisapparatus according to the first embodiment ends the process describedbelow.

First, when performing an ultrasound scanning process on the subject Pinto whom the puncture needle 1 b has been inserted, the scancontrolling unit 18 a causes the ultrasound probe 1 to perform a firstscanning process by transmitting an ultrasound wave in a first directionwith respect to the surface of the vibrators for the purpose of takingan image of the tissue of the subject P and a second scanning process bytransmitting an ultrasound wave in each of a plurality of directionswith respect to the surface of the vibrators. The first scanning processis an ultrasound scanning process performed by transmitting theultrasound wave in the first direction that is optimal for taking theimage of the tissue of the subject P, along an alignment direction ofthe vibrators. More specifically, the first direction is a directionperpendicular to the surface of the vibrators of the ultrasound probe 1.For example, the first direction is a direction perpendicular to alateral direction. As long as the first direction is an ultrasoundtransmission direction that is optimal for taking the image of thetissue of the subject P, the first direction may be a direction otherthan the direction perpendicular to the surface of the vibrators.

In contrast, the second scanning process is an ultrasound scanningprocess performed by transmitting an ultrasound wave in each of theplurality of directions, for the purpose of searching for an ultrasoundtransmission direction that is optimal for taking an image of thepuncture needle 1 b inserted into the subject P. During the secondscanning process, an ultrasound wave is transmitted in each of theplurality of directions, along the alignment direction of the vibrators.More specifically, each of the plurality of directions is a directionother than the direction perpendicular to the surface of the vibratorsof the ultrasound probe 1. For example, each of the plurality ofdirections is a direction other than the direction perpendicular to thelateral direction. The ultrasound transmission directions used duringthe second scanning process may include the first direction. FIG. 2 is adrawing for explaining the scan controlling unit according to the firstembodiment.

In the example shown in FIG. 2, the puncture needle 1 b in inserted fora target site (T). In this situation, as the first scanning process, thescan controlling unit 18 a causes an ultrasound transmission to beperformed in the direction perpendicular to the lateral direction asshown in FIG. 2, in the same manner as in a regular scanning processthat is generally performed to generate a B-mode image. Further, asshown in FIG. 2, the scan controlling unit 18 a causes oblique scanningprocesses to be performed at a plurality of angles “α1, α2, α3, α4, α5,. . . ”, as the second scanning process.

In this situation, the scan controlling unit 18 a causes the secondscanning process to be performed by obtaining the insertion angle “A” ofthe puncture needle 1 b from the internal storage unit 17 and setting aplurality of oblique scan angles in the vicinity of the directionperpendicular to a puncture line that is set based on the insertionangle “A”. For example, the scan controlling unit 18 a calculates anangle “B” forming the direction perpendicular to the puncture line.Further, the scan controlling unit 18 a determines that the secondscanning process should be performed in the range from the angle “B-B₀”to the angle “B-B₁” at intervals of an angle “β”. In this situation, theangles “B₀, B₁, and β” are set by the operator or an administrator ofthe ultrasound diagnosis apparatus. Further, it is possible for theoperator to arbitrarily change any of the angles “B₀, B₁, and β”. It isacceptable if the intervals at which the oblique scanning process isperformed are equal to one another. Alternatively, it is acceptable tovary the intervals in such a manner that the interval is “β1” in an areapositioned close to the angle “B”, whereas the interval is “β2 (whereβ2>β1)” in an area positioned distant from the angle “B”.

The method for obtaining the puncture angle is not limited to theexample described above. For example, it is acceptable to obtain thepuncture angle, based on a detection result of a position sensor.Examples of the position sensor include a magnetic sensor. For example,the magnetic sensor is attached to the puncture needle 1 b, and amagnetic field generating coil is placed in a predetermined position.Further, the magnetic sensor detects a magnetic signal generated by themagnetic field generating coil. Based on a detection result of themagnetic sensor, the scan controlling unit 18 a calculates a coordinateposition of the magnetic sensor with respect to the magnetic fieldgenerating coil. After that, the scan controlling unit 18 a obtains thepuncture angle by calculating the angle between the surface of theultrasound probe 1 and the puncture needle 1 b, based on the coordinateposition of the magnetic sensor.

When it is not possible to obtain the puncture angle by using theattachment angle of the puncture adapter 1 a or a position sensor, e.g.,when the puncture process is performed in a free-hand manner withoutusing the adapter or a sensor function, the scan controlling unit 18 acauses the second scanning process to be performed at angular intervalsthat are set in advance.

Further, the image generating unit 14 shown in FIG. 1 generates a firstultrasound image by using a reflected wave received by the ultrasoundprobe 1 during the first scanning process. Further, the image generatingunit 14 generates a group of second ultrasound images that areultrasound images corresponding to the plurality of directions by usingreflected waves received by the ultrasound probe during the secondscanning process. FIG. 3 is a drawing for explaining the imagegenerating unit according to the first embodiment.

More specifically, as shown in FIG. 3, the image generating unit 14generates the first ultrasound image as a subject-body image in whichthe visibility of the tissue in the subject's body is not degraded byartifacts, by using the B-mode data generated by performing the firstscanning process (the regular scanning process).

Further, as shown in FIG. 3, the image generating unit 14 generates thegroup of second ultrasound images that are the ultrasound imagescorresponding to the angles “α1, α2, α3, α4, α5, . . . ”, by using agroup of pieces of B-mode data corresponding to the angles “α1, α2, α3,α4, α5, . . . ” generated by performing the second scanning process (theoblique scanning processes). The group of second ultrasound imagesserves as a group of candidate images used for generating a needle imagein which the visibility of the puncture needle is improved.

Returning to the description of FIG. 1, the image generation controllingunit 181 controls the image generating unit 14 so as to generate theneedle image in which the puncture needle 1 b is rendered with a highlevel of brightness, based on an analysis result obtained by analyzingthe brightness distribution of each member of the group of secondultrasound images. The selecting unit 18 b included in the imagegeneration controlling unit 181 has a function of analyzing thebrightness distribution within each image. Out of the analyzed group ofimages, the selecting unit 18 b selects an image of which the analysisresult satisfies a predetermined condition, as a third ultrasound imagein which the puncture needle 1 b is rendered with a high level ofbrightness. In the first embodiment, the selecting unit 18 b selects thethird ultrasound image in which the puncture needle 1 b is rendered witha high level of brightness, out of the group of second ultrasound imagesgenerated by the image generating unit 14, based on the brightnessdistribution of each of the ultrasound images. In other words, theselecting unit 18 b determines the oblique angle with which the punctureneedle 1 b is rendered with the high level of brightness. In thefollowing sections, the predetermined condition used for selecting thethird ultrasound image according to the first embodiment will beexplained.

For example, the selecting unit 18 b extracts a brightness level of eachof the pixels in each of the images generated as the group of secondultrasound images and generates a histogram (a brightness curve)indicating a brightness distribution. In this situation, because thepuncture needle 1 b is a highly reflective member, a B-mode imagegenerated by transmitting an ultrasound wave in a directionsubstantially perpendicular to the puncture needle 1 b has highfrequency of appearance of pixels each having a high level ofbrightness. Accordingly, the selecting unit 18 b determines an imagehaving the maximum frequency of appearance of brightness levels that areequal to or higher than a predetermined threshold value, based on thehistogram of each of the pixels.

When, however, an ultrasound scanning process is performed at an anglesubstantially perpendicular to the puncture needle 1 b, a multiplereflection artifact occurs in a B-mode image.

To cope with this situation, the selecting unit 18 b selects, out of thegroup of second ultrasound images, an image generated from the reflectedwave received in such an ultrasound transmission performed at the angleclosest to the ultrasound transmission direction used for receiving thereflected wave from which the image having the maximum frequency ofappearance of pixels each having a brightness level equal to or higherthan the predetermined threshold value was generated, as the thirdultrasound image. In other words, the selecting unit 18 b selects, aframe immediately before or immediately after the frame in which pixelshaving high levels of brightness appear with high frequency, as thethird ultrasound image.

For example, the selecting unit 18 b determines the ultrasound imagecorresponding to the angle “α4” shown in FIG. 3, as the image having themaximum frequency of appearance of pixels each having a brightness levelequal to or higher than the predetermined threshold value. Further, theselecting unit 18 b selects the ultrasound image corresponding to theangle “α3” shown in FIG. 3, as the third ultrasound image. In otherwords, the selecting unit 18 b determines the angle “α3” to be theoblique angle with which the puncture needle 1 b is rendered with thehigh level of brightness.

Returning to the description of FIG. 1, the extracting unit 18 cincluded in the image generation controlling unit 181 extracts a highbrightness area in the third ultrasound image selected by the selectingunit 18 b, as a puncture needle area. Further, the extracting unit 18 ccontrols the image generating unit 14 so as to generate a needle imageby using the extracted puncture needle area. FIG. 4 is a drawing forexplaining the extracting unit according to the first embodiment.

For example, the operator sets an extraction-purpose threshold valueused for extracting the high brightness area, in advance. Further, asshown in FIG. 4, the extracting unit 18 c extracts a high brightnessarea N having brightness levels equal to or higher than theextraction-purpose threshold value within the third ultrasound image(the angle “α3”), as the puncture needle area. Further, the extractingunit 18 c notifies the image generating unit 14 of the coordinates ofthe high brightness area N within the third ultrasound image. Whileusing the notified coordinates, the image generating unit 14 generatesthe needle image shown in FIG. 4 by, for example, replacing thebrightness levels with “0” in the area other than the high brightnessarea N within the third ultrasound image.

Alternatively, another arrangement is acceptable in which the extractingunit 18 c extracts, out of the third ultrasound image, a straight-linearea in which a high brightness area substantially forms a straightline, as the puncture needle area. For example, the extracting unit 18 cextracts a straight line by applying a straight-line extraction methodsuch as a Hough transform to the third ultrasound image (the angle“α3”). Further, the extracting unit 18 c notifies the image generatingunit 14 of the coordinates of the extracted straight line. The imagegenerating unit 14 then generates the needle image by using the notifiedcoordinates. In this situation, the operator determines whether theextracting unit 18 c performs the extracting process using theextraction-purpose threshold value or performs the extracting processusing the straight-line extraction method.

Returning to the description of FIG. 1, as shown in FIG. 5, the imagesynthesizing unit 16 generates a synthesized image by synthesizingtogether the first ultrasound image (the subject-body image) and theneedle image generated by the image generating unit 14. FIG. 5 is adrawing for explaining the image synthesizing unit according to thefirst embodiment. In the synthesized image shown in FIG. 5, the targetsite T and the puncture needle 1 b are both rendered clearly.

Returning to the description of FIG. 1, the display controlling unit 18d exercises control so that the synthesized image generated by the imagesynthesizing unit 16 is displayed on the monitor 2.

Next, a process performed by the ultrasound diagnosis apparatusaccording to the first embodiment will be explained, with reference toFIG. 6. FIG. 6 is a flowchart for explaining the process performed bythe ultrasound diagnosis apparatus according to the first embodiment.

As shown in FIG. 6, the ultrasound diagnosis apparatus according to thefirst embodiment judges whether a puncture mode has been started (stepS101). In this situation, if the puncture mode has not been started(step S101: No), the ultrasound diagnosis apparatus according to thefirst embodiment is in a standby state until the puncture mode isstarted.

On the contrary, if the puncture mode has been started (step S101: Yes),the scan controlling unit 18 a controls the ultrasound probe 1 so as toperform the first scanning process and the second scanning process (stepS102).

After that, the image generating unit 14 generates a first ultrasoundimage (a subject-body image) and a group of second ultrasound images (agroup of candidate images) (step S103), so that the selecting unit 18 bselects a third ultrasound image out of the group of second ultrasoundimages (step S104). More specifically, the selecting unit 18 bdetermines the image having the maximum frequency of appearance ofpixels each having a brightness level equal to or higher than thepredetermined threshold value, out of the group of second ultrasoundimages. Subsequently, the selecting unit 18 b selects an image generatedfrom the reflected wave received in such an ultrasound transmissionperformed at the angle closest to the ultrasound transmission directionused for receiving the reflected wave from which the determined imagewas generated, as the third ultrasound image.

After that, the extracting unit 18 c extracts a puncture needle areafrom the third ultrasound image, so that the image generating unit 14generates a needle image based on the puncture needle area extracted bythe extracting unit 18 c (step S105). Subsequently, the imagesynthesizing unit 16 generates a synthesized image by synthesizingtogether the first ultrasound image and the needle image (step S106). Asa result, a synthesized image corresponding to one frame has beengenerated.

Further, the display controlling unit 18 d exercises control so that thesynthesized image is displayed on the monitor 2 (step S107), and it isthen judged whether the puncture mode has ended (step S108). In thissituation, if the puncture mode has not ended (step S108: No), theultrasound diagnosis apparatus returns to step S102 and exercisescontrol so that a scanning process is performed so as to generate asynthesized image corresponding to the next frame.

On the contrary, if the puncture mode has ended (step S108: Yes), theultrasound diagnosis apparatus ends the process. Another arrangement isacceptable in which the display controlling unit 18 d exercises controlso that any of the first ultrasound image, the third ultrasound image,and the group of second ultrasound images is displayed together with thesynthesized image, while positioned next to each other. Also, in theexample described above, the judgment of whether the puncture mode hasended is made after the synthesized image is displayed at step S107;however, it is acceptable to configure the first embodiment so that thejudgment of whether the puncture mode has ended is made after the firstscanning process and the second scanning process are performed at stepS102. In other words, the arrangement is acceptable in which the firstscanning process and the second scanning process are sequentiallyperformed in parallel with the processes at steps S103 through S107.

As explained above, in the first embodiment, when performing theultrasound scanning process on the subject P into whom the punctureneedle 1 b has been inserted, the scan controlling unit 18 a causes theultrasound probe 1 to perform the first scanning process by, forexample, transmitting the ultrasound wave in the direction perpendicularto the lateral direction, as well as the second scanning process by, forexample, transmitting the ultrasound wave in each of the plurality ofdirections other than the direction perpendicular to the lateraldirection. Further, the image generating unit 14 generates the firstultrasound image by using the reflected wave received by the ultrasoundprobe 1 during the first scanning process and generates the group ofsecond ultrasound images that are the ultrasound images corresponding tothe plurality of directions by using the reflected waves received by theultrasound probe 1 during the second scanning process.

After that, the selecting unit 18 b selects the third ultrasound imagein which the puncture needle 1 b is rendered with the high level ofbrightness, out of the group of second ultrasound images generated bythe image generating unit 14, based on the brightness distribution ofeach of the ultrasound images. Further, the extracting unit 18 cextracts the high brightness area within the third ultrasound imageselected by the selecting unit 18 b as the puncture needle area, whereasthe image generating unit 14 is controlled so as to generate the needleimage by using the extracted puncture needle area. After that, the imagesynthesizing unit 16 generates the synthesized image by synthesizingtogether the first ultrasound image and the needle image generated bythe image generating unit 14. The display controlling unit 18 dexercises control so that the synthesized image generated by the imagesynthesizing unit 16 is displayed on the monitor 2.

As explained above, according to the first embodiment, the firstultrasound image, which is the subject-body image, is generated byperforming the first scanning process that is optimal for observing thetissue in the subject's body. Further, according to the firstembodiment, the oblique angle that is optimal for observing the punctureneedle 1 b is selected. Further, according to the first embodiment, theneedle image is generated after extracting the area corresponding to thepuncture needle 1 b, from the third ultrasound image generated byperforming the oblique scanning process at the selected angle. In otherwords, the needle image generated in the first embodiment does notcontain tissues in the subject's body that are rendered unclearly due tothe side-lobe effect, unlike in the conventional example. Accordingly,according to the first embodiment, it is possible to improve thevisibility of both the tissue in the subject's body and the punctureneedle. Further, according to the first embodiment, because it ispossible to display the synthesized image in which the visibility ofboth the tissue in the subject's body and the puncture needle isimproved, it is possible to enhance safety and the precision level ofthe puncture process and thus to aid the operator who performs thepuncture process.

In addition, according to the first embodiment, the selecting unit 18 bdetermines the ultrasound transmission direction used for receiving thereflected wave from which the image having the maximum frequency ofappearance of pixels each having a brightness level equal to or higherthan the predetermined threshold value was generated, from among thegroup of second ultrasound images. Further, the selecting unit 18 bselects the image generated from the reflected wave received in such anultrasound transmission performed at the angle closest to the determinedultrasound transmission direction, as the third ultrasound image.

In other words, an ultrasound image generated by performing an obliquescanning process at the angle exactly perpendicular to the insertiondirection of the puncture needle 1 b has a high possibility ofcontaining a multiple reflection artifact. Thus, even if a highbrightness area is extracted from such an ultrasound image, the needleimage also has a possibility of containing an artifact related to thepuncture needle 1 b. In contrast, the third ultrasound image selected asa result of the process described above has a lower possibility ofcontaining a multiple reflection artifact. Accordingly, the firstembodiment is able to provide the needle image having fewer artifacts.

In addition, in the first embodiment, according to a setting made by theoperator, for example, the extracting unit 18 c extracts thestraight-line area in which the high brightness area substantially formsa straight line, from the third ultrasound image, as the puncture needlearea. In other words, in the first embodiment, only the straight-linepart corresponding to the shape of the puncture needle 1 b is generatedas the needle image. As a result, the first embodiment is able toprovide the needle image in which only the part corresponding to thepuncture needle 1 b is rendered.

In a second embodiment, an example will be explained in which a processto select a third ultrasound image is performed after a brightnessadjusting process is performed on the group of second ultrasound images,with reference to FIG. 7 and so on. FIG. 7 is a diagram for explaining aconfiguration of a controlling unit according to the second embodiment.

As shown in FIG. 7, the controlling unit 18 according to the secondembodiment is different from the controlling unit 18 according to thefirst embodiment shown in FIG. 1, for further including an adjustingunit 18 e. In the following sections, the second embodiment will beexplained while a focus is placed on the difference. In the secondembodiment also, like in the first embodiment, the first ultrasoundimage and the group of second ultrasound images are generated after thefirst scanning process and the second scanning process are performed.

When an ultrasound beam is arranged to be oblique, the brightness levelsof the entire image become higher and the image quality becomesdegraded, due to the side-lobe effect. For this reason, it is desirableto perform a process to make the brightness levels of the entire imageuniform, on the group of images from which the third ultrasound image isselected, so that the brightness levels of the entire image are notdependent on the oblique scan angle.

For this reason, in the second embodiment, the adjusting unit 18 egenerates a group of third ultrasound images in which the brightnesslevels of the entirety of each of the ultrasound images aresubstantially uniform, by performing a brightness adjusting process onthe group of second ultrasound images generated by the image generatingunit 14.

In one example, the adjusting unit 18 e divides each member of the groupof pieces of raw data (the group of pieces of B-mode data) correspondingto the group of second ultrasound images, into a plurality of sections.Further, the adjusting unit 18 e determines whether the signal in eachof the sections is a subject-body signal or a noise signal. Further, theadjusting unit 18 e calculates a gain curve so as to reduce thebrightness levels if the signal is a noise signal and so as to make thebrightness levels spatially uniform if the signal is a subject-bodysignal. Further, the adjusting unit 18 e generates the group of thirdultrasound images from the group of pieces of raw data corresponding tothe group of second ultrasound images, by using the calculated gaincurve. FIG. 8 is a drawing for explaining the adjusting unit accordingto the second embodiment.

As a result of the process described above, the adjusting unit 18 egenerates, as shown in FIG. 8, the ultrasound images (the group of thirdultrasound images) in which the noise is suppressed and the brightnesslevels of the subject-body signals are adjusted. Alternatively, anotherarrangement is acceptable in which the adjusting unit 18 e notifies theimage generating unit 14 of the calculated gain curve and exercisescontrol so that the image generating unit 14 generates the group ofthird ultrasound images.

Further, while using the group of third ultrasound images as a group ofcandidate images, the selecting unit 18 b included in the imagegeneration controlling unit 181 according to the second embodimentselects a third ultrasound image out of the group of third ultrasoundimages. In other words, the selecting unit 18 b selects the thirdultrasound image out of the group of third ultrasound images, by using ahistogram (a brightness curve) indicating the brightness distribution ofeach member of the group of third ultrasound images generated from thesecond ultrasound images, instead of selecting out of the group ofsecond ultrasound images. In the following sections, a predeterminedcondition used for selecting the third ultrasound image according to thesecond embodiment will be explained.

More specifically, by referring to the histogram of each member of thegroup of third ultrasound images, the selecting unit 18 b determines theimage having the maximum frequency of appearance of brightness levelsthat are equal to or higher than the predetermined threshold value andfurther selects the image generated from the reflected wave received insuch an ultrasound transmission performed at the angle closest to theultrasound transmission direction used for receiving the reflected wavefrom which the determined image was generated, as the third ultrasoundimage. For example, the selecting unit 18 b selects the image obtainedas a result of the brightness adjusting process performed by theadjusting unit 18 e on the ultrasound image corresponding to the angle“α4” shown in FIG. 3, as the third ultrasound image.

According to the second embodiment in which the third ultrasound imageis selected out of the group of third ultrasound images on which thebrightness adjusting process has been performed, because the possibilitythat multiple reflection artifacts are reduced is high, it is alsoacceptable to configure the selecting unit 18 b so as to select theimage having the maximum frequency of appearance of brightness levelsthat are equal to or higher than the predetermined threshold value, asthe third ultrasound image. In that situation, for example, theselecting unit 18 b selects the image obtained as a result of thebrightness adjusting process performed by the adjusting unit 18 e on theultrasound image corresponding to the angle “α3” shown in FIG. 3, as thethird ultrasound image.

Further, the extracting unit 18 c included in the image generationcontrolling unit 181 according to the second embodiment extracts apuncture needle area from the third ultrasound image by using the methodexplained in the first embodiment, i.e., the extraction method using anextraction-purpose threshold value or the straight-line extractionmethod.

Further, the image generating unit 14 generates a needle image, so thatthe image synthesizing unit 16 generates a synthesized image. Thesynthesized image is then displayed on the monitor 2 by the displaycontrolling unit 18 d. As explained above, the image generationcontrolling unit 181 according to the second embodiment generates theneedle image by analyzing the brightness distributions, while using as atarget the group of third ultrasound images that are based on theanalysis results obtained by analyzing the brightness distribution ofeach member of the group of second ultrasound images.

The process performed by the ultrasound diagnosis apparatus according tothe second embodiment is the same as the process performed by theultrasound diagnosis apparatus according to the first embodimentexplained with reference to FIG. 6, except that the adjusting unit 18 egenerates, after step S103, the group of third ultrasound images byperforming the brightness adjusting process on the group of secondultrasound images and that the third ultrasound image is selected out ofthe group of third ultrasound images at step S104; thus, the explanationthereof will be omitted. In addition, another arrangement is acceptablein which the display controlling unit 18 d exercises control so that anyof the first ultrasound image, the third ultrasound image, and the groupof third ultrasound images is displayed together with the synthesizedimage, while positioned next to each other. Further, in the secondembodiment also, the arrangement is acceptable in which the firstscanning process and the second scanning process are sequentiallyperformed in parallel with the processes at steps S103 through S107.

As explained above, according to the second embodiment, the adjustingunit 18 e generates the group of third ultrasound images in which thebrightness levels of the entirety of each of the ultrasound images aresubstantially uniform, by performing the brightness adjusting process onthe group of second ultrasound images generated by the image generatingunit 14. Further, the selecting unit 18 b selects the third ultrasoundimage out of the group of third ultrasound images.

In other words, according to the second embodiment, it is possible togenerate the needle image from the ultrasound images on which thebrightness adjusting process has been performed.

In a third embodiment, an example will be explained in which a processto select a third ultrasound image is performed, after an imageprocessing process using the first ultrasound image is performed on thegroup of second ultrasound images.

The controlling unit 18 according to the third embodiment is configuredto be similar to the controlling unit 18 according to the firstembodiment explained with reference to FIG. 1. In the third embodiment,however, the process performed by the selecting unit 18 b included inthe image generation controlling unit 181 is different from theprocesses in the first and the second embodiments. In the followingsections, the third embodiment will be explained, while a focus isplaced on the difference. In the third embodiment also, like in thefirst and the second embodiments, the first ultrasound image and thegroup of second ultrasound images are generated after the first scanningprocess and the second scanning process are performed.

The image generation controlling unit 181 according to the thirdembodiment controls the image generating unit 14 so as to generate aneedle image in which the puncture needle 1 b is rendered with a highlevel of brightness, based on an analysis result obtained by analyzingthe brightness distribution of each member of a group of images based onthe first ultrasound image and the group of second ultrasound images. Inother words, the selecting unit 18 b included in the image generationcontrolling unit 181 according to the third embodiment selects a thirdultrasound image out of the group of images based on the firstultrasound image and the group of second ultrasound images. Morespecifically, the selecting unit 18 b according to the third embodimentcontrols the image generating unit 14 so as to generate a group ofdifference images by subtracting the first ultrasound image from eachmember of the group of second ultrasound images and further selects thethird ultrasound image out of the group of difference images. FIGS. 9and 10 are drawings for explaining the selecting unit according to thethird embodiment.

Under the control of the selecting unit 18 b, the image generating unit14 according to the third embodiment subtracts the first ultrasoundimage (the subject-body image) from the group of second ultrasoundimages respectively corresponding to the angles “α1, α2, α3, α4, α5, . .. ”, as shown in FIG. 9. In other words, the image generating unit 14generates a difference image corresponding to each of the angles “α1,α2, α3, α4, α5, . . . ”. As a result, the image generating unit 14generates the group of difference images that serve as a group ofcandidate images. Further, the selecting unit 18 b according to thethird embodiment selects the third ultrasound image by performing abrightness analysis on the group of difference images. In the followingsections, a predetermined condition used for selecting the thirdultrasound image according to the third embodiment will be explained.

First, like in the first and the second embodiments, the selecting unit18 b generates a histogram (a brightness curve) indicating thebrightness distribution of each of the difference images. In thissituation, there is a high possibility that only the puncture needle 1 bis extracted into each of the difference images. In other words, in adifference image in which the puncture needle 1 b is rendered clearly,because a high brightness area appears only in a certain part, thebrightness curve has a large distribution of low brightness levels and asmall distribution of high brightness levels, as shown by a curve “a” inFIG. 10. In contrast, in a difference image in which the puncture needle1 b is rendered unclearly, because a medium brightness area appears onlyin a certain part, the brightness curve has a large distribution of lowbrightness levels and medium brightness levels, as shown by a curve “b”in FIG. 10.

For this reason, the selecting unit 18 b selects one of the differenceimages that exhibits a brightness curve like the curve “a” in FIG. 10,as the third ultrasound image. For example, the selecting unit 18 bselects the difference image generated by subtracting the firstultrasound image from the ultrasound image corresponding to the angle“α3” shown in FIG. 9, as the third ultrasound image.

Further, the extracting unit 18 c included in the image generationcontrolling unit 181 according to the third embodiment extracts theentire third ultrasound image selected by the selecting unit 18 b as apuncture needle area. In other words, in the third embodiment, the thirdultrasound image itself is used as a needle image.

Alternatively, another arrangement is acceptable in which the extractingunit 18 c according to the third embodiment extracts a high brightnessarea within the third ultrasound image selected by the selecting unit 18b, as a puncture needle area. In other words, it is acceptable if theextracting unit 18 c according to the third embodiment extracts thepuncture needle area from the third ultrasound image, by using anextraction method that uses an extraction-purpose threshold value or astraight-line extraction method. In that situation, the image generatingunit 14 generates a needle image by using the puncture needle area,under the control of the extracting unit 18 c, like in the firstembodiment.

The operator is able to select whether the entire third ultrasound imageis extracted as a puncture needle area or the high brightness areawithin the third ultrasound image is extracted as a puncture needlearea.

Next, a process performed by an ultrasound diagnosis apparatus accordingto the third embodiment will be explained, with reference to FIG. 11.FIG. 11 is a flowchart for explaining the process performed by theultrasound diagnosis apparatus according to the third embodiment.

As shown in FIG. 11, the ultrasound diagnosis apparatus according to thethird embodiment judges whether a puncture mode has been started (stepS201). In this situation, if the puncture mode has not been started(step S201: No), the ultrasound diagnosis apparatus according to thethird embodiment is in a standby state until the puncture mode isstarted.

On the contrary, if the puncture mode has been started (step S201: Yes),the scan controlling unit 18 a controls the ultrasound probe 1 so as toperform the first scanning process and the second scanning process (stepS202).

After that, the image generating unit 14 generates a first ultrasoundimage (a subject-body image) and a group of second ultrasound images (agroup of candidate images) (step S203). Under the control of theselecting unit 18 b, the image generating unit 14 further generates agroup of difference images by subtracting the first ultrasound imagefrom each member of the group of second ultrasound images (step S204).

Subsequently, the selecting unit 18 b selects a third ultrasound imageout of the group of difference images (step S205). More specifically,the selecting unit 18 b selects one of the difference images exhibitingsuch a brightness curve that has high frequency of appearance of lowbrightness levels and low frequency of appearance of high brightnesslevels, as the third ultrasound image.

After that, the extracting unit 18 c extracts the entire thirdultrasound image as a puncture needle area, so that the image generatingunit 14 generates the third ultrasound image as a needle image (stepS206). Alternatively, another arrangement is acceptable in which theextracting unit 18 c extracts a puncture needle area from the thirdultrasound image, by using an extraction-purpose threshold value or astraight-line extraction method, so that the image generating unit 14generates a needle image by using the puncture needle area.

Subsequently, the image synthesizing unit 16 generates a synthesizedimage by synthesizing together the first ultrasound image and the needleimage (step S207). As a result, a synthesized image corresponding to oneframe has been generated.

Further, the display controlling unit 18 d exercises control so that thesynthesized image is displayed on the monitor 2 (step S208), and it isthen judged whether the puncture mode has ended (step S209). In thissituation, if the puncture mode has not ended (step S209: No), theultrasound diagnosis apparatus returns to step S202 and exercisescontrol so that a scanning process is performed so as to generate asynthesized image corresponding to the next frame.

On the contrary, if the puncture mode has ended (step S209: Yes), theultrasound diagnosis apparatus ends the process. Another arrangement isacceptable in which the display controlling unit 18 d exercises controlso that any of the first ultrasound image, the third ultrasound image,and the group of difference images is displayed together with thesynthesized image, while positioned next to each other. Also, in theexample described above, the judgment of whether the puncture mode hasended is made after the synthesized image is displayed at step S208;however, it is acceptable to configure the third embodiment so that thejudgment of whether the puncture mode has ended is made after the firstscanning process and the second scanning process are performed at stepS202. In other words, the arrangement is acceptable in which the firstscanning process and the second scanning process are sequentiallyperformed in parallel with the processes at steps S203 through S208.

As explained above, in the third embodiment, the selecting unit 18 bcontrols the image generating unit 14 so as to generate the group ofdifference images by subtracting the first ultrasound image from eachmember of the group of second ultrasound images and further selects thethird ultrasound image out of the group of difference images. Afterthat, the extracting unit 18 c extracts the entire third ultrasoundimage selected by the selecting unit 18 b or the high brightness areawithin the third ultrasound image, as the puncture needle area.

In other words, in the third embodiment, the third ultrasound image isselected out of the group of difference images in each of which theinformation about the tissue in the subject's body is reduced. As aresult, according to the third embodiment, it is possible to furtherimprove the visibility of the puncture needle 1 b, compared to theexample in which the third ultrasound image is selected out of the groupof images generated by performing an oblique scanning process. Also, inthe first and the second embodiments described above, it is acceptableto extract the entire third ultrasound image as a puncture needle area,if the effect of artifacts on the tissue in the subject's body renderedin the third ultrasound image is small.

As a fourth embodiment, an example will be explained in which thebrightness adjusting process explained in the second embodiment isperformed with the third embodiment.

The controlling unit 18 according to the fourth embodiment is configuredby adding the adjusting unit 18 e explained in the second embodiment tothe controlling unit 18 according to the third embodiment. In otherwords, the configuration of the controlling unit 18 according to thefourth embodiment is the same as that of the controlling unit 18 shownin FIG. 7.

More specifically, in the fourth embodiment also, like in the first tothe third embodiments, the first ultrasound image and the group ofsecond ultrasound images are generated after the first scanning processand the second scanning process are performed. FIGS. 12A and 12B aredrawings for explaining a process performed by the controlling unitaccording to the fourth embodiment.

Further, in the fourth embodiment, like in the second embodiment, theadjusting unit 18 e generates a group of third ultrasound images inwhich the brightness levels of the entirety of each of the ultrasoundimages are substantially uniform, by performing the brightness adjustingprocess on the group of second ultrasound images (step SA1 shown in FIG.12A).

After that, in the fourth embodiment, unlike in the third embodiment,the image generating unit 14 generates, under the control of theselecting unit 18 b, a group of difference images from the group ofthird ultrasound images (step SA2 shown in FIG. 12A). In other words,the image generating unit 14 generates the group of difference images bysubtracting each member of the group of third ultrasound images from thefirst ultrasound image.

Subsequently, in the fourth embodiment, a third ultrasound image isselected out of the group of difference images generated by using thegroup of third ultrasound images (step SA3 shown in FIG. 12A). In otherwords, in the example shown in FIG. 12A, the selecting unit 18 bcontrols the image generating unit 14 so as to generate the group ofdifference images from the group of third ultrasound images and furtherselects the third ultrasound image out of the group of differenceimages. In this situation, the predetermined condition used forselecting the third ultrasound image in the example shown in FIG. 12A isthe selecting condition explained in the third embodiment.

As explained above, in the fourth embodiment, the processes at steps SA1through SA3 shown in FIG. 12A are performed, in place of the processesat steps S204 and S205 explained with reference to the flowchart in FIG.11.

As a result, according to the fourth embodiment, because the imagequality of the group of difference images out of which the thirdultrasound image is selected is improved, it is possible to furtherimprove the visibility of the puncture needle 1 b compared to the thirdexample.

It should be noted that, however, as mentioned earlier, in actualultrasound images, the same site is seldom rendered with the same levelof brightness by performing the oblique scanning processes, even if thebrightness adjusting process is performed on the entirety of each imageduring the image acquiring process. Accordingly, there is a possibilitythat a difference image generated by using the third ultrasound image onwhich the brightness adjusting process has been performed may containsome areas in which the tissue in the subject's body that failed to beeliminated is rendered. For this reason, it is acceptable to configurethe fourth embodiment so as to further include the process describedbelow, as a modification example.

First, the adjusting unit 18 e further performs a brightness adjustingprocess on the group of difference images (step SA4 shown in FIG. 12B).More specifically, the adjusting unit 18 e further performs thebrightness adjusting process to make the brightness levels of theentirety of each of the difference images substantially uniform, on thegroup of difference images generated by the image generating unit 14. Inother words, the adjusting unit 18 e performs the brightness adjustingprocess that was performed on the group of second ultrasound images,also on the group of difference images. With this arrangement, it ispossible to eliminate residue areas showing the tissue in the subject'sbody that are contained in the difference images.

Alternatively, another arrangement is acceptable in which the adjustingunit 18 e performs a brightness adjusting process on the group ofdifference images, by replacing any brightness level equal to or lowerthan a second threshold value with a predetermined value. For example,the second threshold value is set by referring to the brightness levelscorresponding to the residues showing the tissue in the subject's body.Further, for example, the adjusting unit 18 e replaces each of thebrightness levels equal to or lower than the second threshold value with“0”. With this arrangement also, it is possible to eliminate the residueareas showing the tissue in the subject's body that are contained thedifference images.

After that, the selecting unit 18 b selects a third ultrasound image outof the group of difference images on which the brightness adjustingprocess has been performed by the adjusting unit 18 e (step SA5 shown inFIG. 12B). In this situation, the predetermined condition used forselecting the third ultrasound image in the example shown in FIG. 12B isthe selecting condition explained in the third embodiment.

As explained above, in the modification example of the fourthembodiment, steps SA1 and SA2 shown in FIG. 12A and steps SA4 and SA5shown in FIG. 12B are sequentially performed, in place of the processesat steps S204 and S205 explained with reference to the flowchart in FIG.11.

As a result, in the modification example of the fourth embodiment, thegroup of difference images from which the third ultrasound image isselected has a lower possibility of having the residues showing thetissue in the subject's body rendered. Thus, it is possible to furtherimprove the visibility of the puncture needle 1 b, compared to theexamples described above. Like in the third embodiment, in the fourthembodiment and the modification example of the fourth embodiment, it isacceptable if the entire third ultrasound image is extracted as apuncture needle area or if a high brightness area within the thirdultrasound image is extracted as a puncture needle area.

It is acceptable to configure the image synthesizing unit 16 accordingto any of the first to the fourth embodiments described above, so as togenerate the synthesized image by superimposing the first ultrasoundimage (the subject-body image) and the needle image with each othersimply in a one-on-one manner, or so as to perform a synthesizingprocess described below. FIG. 13 is a drawing for explaining amodification example of the image synthesizing unit.

More specifically, the image synthesizing unit 16 generates asynthesized image by changing the weights used for synthesizing togetherthe first ultrasound image and the needle image. For example, as shownin FIG. 13, the image synthesizing unit 16 generates a synthesized imagein which the puncture needle 1 b is emphasized, by setting the weightfor the subject-body image to “1” and setting the weight for the needleimage to “2”. In this situation, the operator is able to arbitrarilychange the weight for each of the images and is able to change theweights, for example, even during medical practice. In other words, whenthe operator wishes to refer to a synthesized image in which thepuncture needle 1 b is emphasized, the operator increases the weight forthe needle image, whereas when the operator wishes to refer to asynthesized image in which the tissue in the subject's body isemphasized, the operator increases the weight for the subject-bodyimage. For example, the weight for each of the images is set via theinput device 3.

Another arrangement is also acceptable in which the image synthesizingunit 16 generates a plurality of synthesized images by varying theweights. For example, it is acceptable to configure the imagesynthesizing unit 16 so as to generate two synthesized images in whichthe weights between the subject-body image and the needle image is “1:2”and “2:1”, respectively. Further, it is also acceptable to configure theimage synthesizing unit 16 so as to additionally generate a synthesizedimage in which the subject-body image and the needle image aresynthesized together with “1:1” weights, even when it is requested thatthe image synthesizing unit 16 should generate a synthesized image inwhich the weights are changed. In that situation, the displaycontrolling unit 18 d displays the plurality of synthesized images so asto be positioned next to one another.

According to the modification example described above, it is possible todisplay, in response to the request from the operator (the medicaldoctor), the synthesized images in which one of the tissue in thesubject's body and the puncture needle 1 b is emphasized. It istherefore possible to further aid the puncture process performed by theoperator.

Further, in the first to the fourth embodiments described above, theexample is explained in which the plurality of ultrasound transmissiondirections used for performing the second scanning process are fixed;however, it is also acceptable to perform the second scanning processaccording to any of the first to the fourth embodiments, as in amodification example described below.

Specifically, the scan controlling unit 18 a according to thismodification example changes the ultrasound transmission condition usedin the second scanning process, based on the ultrasound transmissiondirection used for receiving the reflected wave from which the thirdultrasound image selected by the selecting unit 18 b was generated.FIGS. 14A and 14B are drawings for explaining the modification exampleof the scan controlling unit.

In one example, the scan controlling unit 18 a first causes a secondscanning process to be performed in a predetermined angle range (a rangefrom the angle “B-B₀” to the angle “B-B₁”) at 10-degree intervals, asshown in FIG. 14A. In this situation, let us assume that, for example,the selecting unit 18 b has selected the third ultrasound imagegenerated by performing the oblique scanning process corresponding tothe angle “α3”, as shown in FIG. 14A. In that situation, for example,the scan controlling unit 18 a determines the angle “α3” to be acandidate angle used for generating a needle image as shown in FIG. 14Aand further causes a second scanning process to be performed again whilearranging “the intervals from α2 to α4 to be 5-degree intervals”centered around the angle “α3”.

Further, the selecting unit 18 b selects a third ultrasound image out ofthe group of images generated by performing the second scanning processagain. It is also acceptable to repeatedly perform the second scanningprocess three or more times. For example, an arrangement is acceptablein which the second scanning process is repeatedly performed apredetermined number of times, while gradually decreasing the angularintervals and the angle range.

According to the modification example described above, it is possible toselect the oblique angle optimal for generating the needle image, with ahigh level of precision.

The modification applied to the second scanning process is not limitedto the example described above in which the second scanning process isrepeatedly performed for generating the synthesized image correspondingto one frame. For instance, another arrangement is acceptable in whichthe angular intervals and the angle range in the second scanning processperformed for generating a new frame are decreased, based on the obliqueangle used for generating the third ultrasound image selected in theimmediately preceding the frame. With this arrangement, it is possibleto reduce the processing load required in the synthesized imagegenerating process. In particular, when the brightness adjusting processis performed, it is possible to reduce the quantity of images on whichthe brightness adjusting process is performed.

Further, the second scanning process does not necessarily have to beperformed in a plurality of directions. For example, an arrangement isacceptable in which the scan controlling unit 18 a determines theultrasound transmission direction used for receiving the reflected wavefrom which the third ultrasound image selected by the selecting unit 18b was generated, to be a second direction that serves as the ultrasoundtransmission direction used for performing the second scanning process.For example, let us assume that, as shown in FIG. 14B, the selectingunit 18 b has selected the third ultrasound image generated byperforming the oblique scanning process corresponding to the angle “α3”.In that situation, as shown in FIG. 14B, it is acceptable to configurethe scan controlling unit 18 a so as to determine, for the followingframes, the ultrasound transmission direction corresponding to the angle“α3” to be the second direction and so as to perform the second scanningprocess while fixing the ultrasound transmission direction to the seconddirection. When the angle used in the second scanning process is fixed,the process performed by the selecting unit 18 b is skipped so that aneedle image is generated from the image generated by performing anoblique scanning process corresponding to the angle “α3” as a result ofthe process performed by the extracting unit 18 c.

In this situation, the transition from the second scanning processperformed in a plurality of directions to the second scanning processperformed in a single direction can be roughly divided into the variouspatterns described below: In a first pattern, the oblique scan angle isdetermined in the first frame, so that a transition is made from thesecond scanning process performed in a plurality of directions, to thesecond scanning process performed in a single direction. In a secondpattern, the second scanning process is performed in a plurality ofdirections for two or more frames, so that if the oblique scan angleselected in each of the frames is within a predetermined range, atransition is made from the second scanning process performed in theplurality of directions, to the second scanning process performed in asingle direction. In that situation, it is possible to use an averagevalue or a median as the fixed oblique scan angle.

In these examples described above, it is also possible to reduce theprocessing load required in the synthesized image generating process.

Further, it is also acceptable to configure the scan controlling unit 18a so as to employ both the second scanning process performed in aplurality of directions and the second scanning process performed in asingle direction, in the manner described below: After determining thesecond direction, the scan controlling unit 18 a causes the selectingunit 18 b to perform again, at a predetermined time, the process ofselecting a third ultrasound image, while arranging the ultrasoundtransmission directions used in the second scanning process to be aplurality of directions. Further, the scan controlling unit 18 adetermines the ultrasound transmission direction used for receiving thereflected wave from which the third ultrasound image selected by theselecting unit 18 b was generated, as a new second direction. In thissituation, the predetermined time at which the second direction isupdated may be a point in time specified by the operator or may be apoint in time when a period of time set in advance has elapsed. Forexample, the scan controlling unit 18 a exercises control so that, evenafter a transition is made to the second scanning process performed inthe single direction (the second direction), the second scanning processis performed in a plurality of directions, either once or two or moretimes, at predetermined intervals (e.g., once in every five frames). Inthis manner, the scan controlling unit 18 a determines again the obliquescan angle (the new second direction) used for performing the secondscanning process in a single direction.

In the examples described above, it is possible to reduce the processingload required in the synthesized image generating process, whilesequentially updating the optimal oblique angle used for generating theneedle image.

In the description above, the examples in which one third ultrasoundimage is selected are explained; however, in some situations, there maybe a plurality of images that satisfy the “predetermined condition”explained in the first to the fourth embodiments. In the followingsections, a process to be performed when the selecting unit 18 b hasselected a plurality of images satisfying the predetermined conditionwill be explained.

When having selected a plurality of images satisfying the predeterminedcondition, the selecting unit 18 b controls the image generating unit 14so as to generate an addition image obtained by adding together theselected plurality of images. For example, the image generating unit 14generates the addition image by adding together the plurality of imagesselected by the selecting unit 18 b. Alternatively, for example, theimage generating unit 14 generates the addition image by calculating anarithmetic mean of the plurality of images selected by the selectingunit 18 b. Further, it is also acceptable to configure the selectingunit 18 b so as to, for example, set a weight used for generating theaddition image for each of the selected plurality of images, based on adegree of matching with the predetermined condition for each of theselected images.

Further, the extracting unit 18 c performs the process to extract apuncture needle area while using the addition image as the thirdultrasound image. By using the addition image, it is possible togenerate a needle image in which the puncture needle 1 b is furtheremphasized.

When a plurality of third ultrasound images have been selected, it isacceptable to configure the scan controlling unit 18 a so as to changethe ultrasound transmission condition used in the second scanningprocess, based on the plurality of ultrasound transmission directionsused for receiving the reflected waves from which the plurality of thirdultrasound images were generated. For example, when the oblique scanangles corresponding to three selected images are “α3, α4, and α5”, itis acceptable to configure the scan controlling unit 18 a to cause asecond scanning process to be performed, while using the threeultrasound transmission directions defined by the angles “α3, α4, andα5” as “three ‘second directions’”. Further, when the second scanningprocess is performed while fixing the ultrasound transmission directionsto the plurality of second directions, it is acceptable to perform againa process to update the ultrasound transmission directions used in thesecond scanning process, at a predetermined time. In that situation, thesecond directions may be updated to a single direction or to a pluralityof directions.

Alternatively, it is also acceptable to configure the selecting unit 18b so as to, after having selected a plurality of images satisfying thepredetermined condition, further select one of the selected plurality ofimages. For example, it is acceptable to configure the selecting unit 18b so as to notify the extracting unit 18 c of the one of the imagesarbitrarily selected out of the selected plurality of images, as a thirdultrasound image. Alternatively, it is acceptable to configure theselecting unit 18 b so as to, for example, notify the extracting unit 18c of the image that best matches the predetermined condition among theselected plurality of images, as a third ultrasound image.

Further, if the selecting unit 18 b has selected a plurality of imagessatisfying the predetermined condition, but is unable to further selectan image that best matches the predetermined condition from among theselected plurality of images, it is acceptable configure the scancontrolling unit 18 a so as to exercise control in the following manner:The scan controlling unit 18 a causes the second scanning process to beperformed again with a decreased angular interval and a decreased anglerange, once or two or more times, as explained with reference to FIG.14A, until the selecting unit 18 b selects one third ultrasound image.Further, the selecting unit 18 b selects the image that best matches thepredetermined condition out of the group of images generated from thesecond scanning process performed again, as a third ultrasound image.

It is possible to realize the controlling method explained in any of thefirst to the fourth embodiments and the modification examples by causinga computer such as a personal computer or a workstation to execute acontrol program prepared in advance. It is possible to distribute thecontrol program via a network such as the Internet. Further, it is alsopossible to record the control program onto a computer-readablenon-temporary recording medium such as a hard disk, a flexible disk(FD), a Compact Disk Read-Only memory (CD-ROM), a Magneto-Optical (MO)disk, a Digital Versatile Disk (DVD), a flash memory like a UniversalSerial Bus (USB) memory and a Secure Digital (SD) card, or the like, sothat a computer reads the control program from the non-temporaryrecording medium and executes the control program.

As explained above, according to the first to the fourth embodiments andthe modification examples, it is possible to improve the visibility ofboth the tissue in the subject's body and the puncture needle.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. An ultrasound diagnosis apparatus comprising: processing circuitry configured to generate ultrasound images of a scan region including a puncture needle inserted in a subject based on outputs from an ultrasound probe, generate first images, each of the first images generated by a comparison of at least two images included in the ultrasound images, extract a region representing a position of the puncture needle from a second image included in the first images, and generate an emphasized image in which at least a part of the extracted region are emphasized.
 2. An ultrasound diagnosis apparatus according to the claim 1, wherein the processing circuitry is configured to suppress a pixel value of a first region other than a second region regarding the puncture needle in the second image, and extract the region representing the position of the puncture needle from the second image in which the pixel value of the first region are suppressed.
 3. An ultrasound diagnosis apparatus according to the claim 1, wherein the processing circuitry is configured to generate each of the first images by a comparison of two images included in the ultrasound images.
 4. An ultrasound diagnosis apparatus according to the claim 2, wherein the processing circuitry is configured to generate each of the first images by a comparison of two images included in the ultrasound images.
 5. An ultrasound diagnosis apparatus according to the claim 3, wherein the processing circuitry is configured to generate each of the first images by a subtraction between two images included in the ultrasound images, pairs of the subtraction being different with respect to each of the first images.
 6. An ultrasound diagnosis apparatus according to the claim 4, wherein the processing circuitry is configured to generate each of the first images by a subtraction between two images included in the ultrasound images, pairs of the subtraction being different with respect to each of the first images.
 7. An ultrasound diagnosis apparatus according to the claim 1, wherein the ultrasound images are different in the steering angle of the scan.
 8. An ultrasound diagnosis apparatus according to the claim 1, wherein the emphasized image is generated by emphasizing at least a part of the extracted region of an ultrasound image.
 9. A method for generating an emphasized image comprising: scanning a scan region including a puncture needle inserted in a subject with ultrasounds; generating ultrasound images of the scan region as a result of the scanning; generating first images, each of the first images generated by a comparison of at least two images included in the ultrasound images, extracting a region representing a position of the puncture needle from a second image included in the first images, and generating an emphasized image in which at least a part of the extracted region are emphasized. 